玉米纹枯病菌Rhizoctonia solani拮抗菌gfj-4的鉴定及其发酵上清液抑菌特性

为了明确菌株gfj-4对植物病原菌的拮抗作用及其在植物病害生物防治中的应用潜力。通过形态特征、生理生化及16S rDNA序列对菌株gfj-4进行鉴定,以玉米纹枯病菌(Rhizoctonia solani)为指示菌,采用菌丝生长速率法测定了不同稀释倍数发酵上清液、不同培养时间、接种量和pH值对抑菌活性的影响,以及从发酵上清液中提取的脂肽类物质的抑菌活性;采用牛津杯法测定了脂肽类物质对其他16种植物病原菌的抑菌效果。初步鉴定菌株gfj-4为解淀粉芽孢杆菌(Bacillus amyloliquefaciens);菌株gfj-4的发酵上清液对玉米纹枯病菌菌丝生长具有显著的抑制作用,稀释倍数从8倍增大到25倍时,其对病菌的抑制率为31.1%~92.4%,发酵上清液对玉米纹枯病菌的EC₅₀为53.1 μL·mL^-1;培养时间96 h,发酵上清液12倍稀释液对玉米纹枯病菌的抑制率最高,为82.0%;接种量为0.5%(V/V)时,对病菌的抑制率最高,为83.2%;pH为7时抑菌率达最高(82.6%)。脂肽类物质稀释60~180倍,对玉米纹枯病菌的抑制率为43.8%~92.0%,脂肽类物质对玉米纹枯病菌的EC₅₀为5.90 μL·mL^-1;与对照相比较,经脂肽类物质处理的玉米纹枯病菌菌丝生长量减少,生长稀疏,而且气生菌丝也受到明显抑制。脂肽类物质对其他16种植物病原菌也具有较高的抑菌活性,抑菌带宽为16.7~31.0 mm,对玉米小斑病菌(Bipolaris maydis)的抑制效应最强,对油菜菌核病菌(Sclerotinia sclerotiorum)的抑制活性最弱。

Identification of antagonistic bacteria gfj-4 to maize sheath blight pathogen and antifungal activity of its fermentation supernatant

The study aimed to clarify the antagonistic effect of strain gfj-4 on plant pathogens and its potential in biological control of plant diseases. The traditional morphology, physiological-biochemical properties as well as 16S rDNA gene sequence analysis were applied to the bacteria classification. The pathogen of maize sheath blight worked as the indicator, the fermentation supernatant with different dilution times, and the culture time, inoculation amount and pH value on the antifungal activity of Rhizoctonia solani were determined by mycelial growth rate method. The inhibition of lipopeptides extracted from fermentation supernatant on the other 16 plant pathogens were determined by oxford cup method. It showed that the strain gfj-4 was identified as Bacillus amyloliquefaciens. The fermentation supernatant of strain gfj-4 had significant inhibitory activity on the mycelial growth, and the inhibition rate was from 31.1% to 92.4% within the dilution factor expanded from 8 to 25 times. The EC₅₀ of fermentation supernatant to R. solani was 53.1 μL·mL^-1. The highest inhibition rate of 12-fold dilution of fermentation supernatant was 82.0% when incubation time was 96 h, and the inhibition rate to R. solani was 83.2% when the inoculation amount was 0.5% (V/V), the inhibitory rate reached 82.6% when the pH value was 7.0. The inhibition ratio of the crude lipopeptides diluted from 60 to 180 times extracted from the fermentation broth was from 43.8% to 92.0%. The EC₅₀ of lipopeptides to R. solani was 5.90 μL·mL^-1. Compared with the control group, it was found that the mycelia growth of R. solani was reduced and the growth of mycelium was sparse, and the aerial mycelium was also inhibited significantly. The inhibitory effects of lipopeptides on the other 16 plant pathogens were also investigated and the inhibition zones were from 16.7 to 31.0 mm, and the inhibitory effect on the Bipolaris maydis was the strongest, while it had the weakest inhibitory activity against Sclerotinia sclerotiorum.